1. Field of the Invention
The present invention relates generally to oil field service equipment, and more particularly, but not by way of limitation, to a downhole well fishing assembly for recovery of a separated downhole sucker rod.
2. Brief Description of the Prior Art.
The prior art is replete with various types of fishing tools for recovering separated or broken downhole sucker rods. For example, U.S. Pat. No. 2,272,529 (Larson) discloses a fishing tool for recovering a separated sucker rod comprising a rotatable barrel body having an eccentric sleeve. The eccentric sleeve, by selective rotation of the barrel body, is adapted to grip the downhole sucker rod portion that has separated. Once gripped, the fishing tool is brought to the surface, pulling the separated sucker rod with it.
Taylor, U.S. Pat. No. 4,185,865, discloses a fishing tool or overshot operable on a wire line for recovery of a separated downhole sucker rod. The fishing tool comprises a retractable set of collet fingers mounted in an overshot body. The collect fingers are engageable with the downhole member to be retrieved (i.e. a fish). Repeated bumping of the collet fingers against the fish extending into the collet fingers results in the opening or closing of the collet fingers via cam actuated internal rotation of the collet fingers. Thus, the fish pulls the collet fingers into gripping engagement as it pulls the closed collet fingers through a tapered opening in the overshot body. U.S. Pat. No. 4,548,437, issued to Driskill, discloses a fishing assembly having the ability to exercise positive control at the surface over subsurface, downhole fishing assemblies. The fishing tool comprises a body member having an offset entrance port into a cylindrical cavity that contains a slide member having a cylindrically-shaped upper portion and a trough-shaped lower portion. The trough-shaped lower portion is positionable adjacent the entrance port in either of two diametrically opposed angular positions to alternatively capture or release an enlargement on a rod inserted into the body member cavity via the entrance port. Grooves are cut into the cylindrically-shaped upper portion. A pin, mounted in the body member, engages the grooves such that the slide member is caused to rotate one half turn when the slide member is reciprocated in the cavity.
The fishing assembly of the Driskill patent also includes a tubular collet support barrel extending from the lower end of the body member to receive a collet. The collet includes a shank and an enlarged upper end so that the collet can be held in a raised position in one of the two angular positions of the slide member and the body member, or can be released to fall to the bottom of the collet support barrel in the other of the two angular positions of the slide member and the body member.
Each of the devices taught by the before-mentioned patents constituted improvement in an area occupied by numerous prior art fishing devices, especially the device taught by Driskill because of the ability of the device to exercise position control at the surface over subsurface, downhole fishing assemblies. However, even with such improvements in downhole fishing devices, the need remains for improved fishing devices which are capable of capturing either the enlarged portion of a separated downhole sucker rod or the body portion of such sucker rod, while being economical to manufacture and substantially maintenance free. It is to such a downhole well fishing assembly that the subject invention is directed.